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At least 19 recordsLinked to original sources

PubMed1975

Spermatogenesis in Anthozoa: differentiation of the spermatid.

The fine structure of spermatids has been examined in Calliactis, Protanthea, Gonactinia and Parazoanthus (Cnidaria, Anthozoa). The sperm cells are relatively simple and lack distinct acrosomes. Their nuclei, spherical in the zoanthid, in the actinians are slendertipped cones. Condensation of the chromatin is interpreted in terms of progressive coiling of densely-stained filaments and the elimination of nucleoplasm. Nuclear elongation occurs in the absence of microtubules. A well-developed centriolar complex is attached to the nuclear envelope by fibres and in this area (that of a shallow fossa in actinian spern) the nuclear membranes seem to be thickened. The centrioles are surrounded by a mitochondrial collar, especially pronounced in Calliactis. In contact with the mitochondria and nucleus is a ring of lipid-containing vesicles 300-700 nm in diameter. A system of densely-staining vesicles 150-300 nm in size corresponds to the "pro-acrosomal vesicles" described for other coelenterates. They are scattered in the peripheral cytoplasm and are regarded as derivatives of the endoplasmic reticulum. Problems of organelle function and of differentiation during spermiogenesis are discussed.

Animals↗

PubMed1977

[Ultrastructural localization of acid and alkaline phosphatases in sterile septae of the anthozoa Pachycerianthus fimbriatus (author's transl)].

Acid and alkaline phosphatase activity has been localized in the cells of the sterile septae of starved and fed anthozoa. Acid phosphatase is present in lysosomes, in Golgi cisternae and old phagosomes of starved animals. In fed animals, the reaction is more intense and the number of lysosomes is increased. New phagosomes are loaded with lead phosphate. In starved animals, the alkaline phosphatase activity has been observed on the plasma membranes and in the old phagosomes.

Acid Phosphatase↗

PubMed1975

Colonial conduction systems in the Anthozoa: Octocorallia.

1. The octocorals Alcyonium digitatum, Pennatula phosphorea and Virgularia mirabilis each have a through-conducting nerve net. The nerve net demonstrated electrophysiologically may well be the same as that previously shown by the use of histological techniques. 2. It exhibits both facilitation and defacilitation in the rate of conduction of pulses. 3. The distance of spread of nerve net activity is not limited by the number of stimuli applied. 4. The nerve net controls fast muscle contractions; the frequency of pulses is important in determining which muscles contract and in which sequence. 5. The nerve net is 'spontaneously' active. 6. A previously undescirbed slow system has been identified in Pennatula. It has many of the properties of slow systems in sea anemones and may well be ectodermal. It is suggested that multiple conduction systems are of common occurrence in the Anthozoa.

Animals↗

PubMed1979

[Genesis of connective matrix of Veretillum cynomorium Pall. (Cnidaria-Anthozoa). Ultrastructural and autoradiographic study (author's transl)].

Ultrastructural study of the tissues of Veretillum cynomorium shows the presence of two mesenchymatous cellular states in the mesoglea: the nongranular mesenchymatous cells and the granular mesenchymatous cells. These latter possess, besides their cytoplasmic granules, some homogeneous fibrous inclusions, very similar to the fibrous material of the mesoglea. Granules and homogeneous fibrous inclusions are also present in the cytoplasm of some ectodermic and endodermic cells. These morphological results lead us to consider that mesoglea and epithelia can be occupied by the same granular cell type. Besides this, the digestive endodermic cells are sometimes very rich in heterogeneous fibrous inclusions histochemically identified as phagosomes. An autoradiographic study indicates two possible pathways for the synthesis of the mesoglea. The first involves the endoderm which elaborates the mesoglea at a fast rate but in small amounts. The second is due to the granular cells (mesenchymatous and epithelial) which show a slow rate of synthesis leading to the formation of the homogeneous fibrous inclusions. The heterogeneous fibrous inclusions of the digestive endodermic cell support the hypothesis of the involvement of these cells in mesogleal degradation.

Animals↗

PubMed1975

Chemical nature of bioluminescence systems in coelenterates.

Analysis of substances involved in light-emitting reactions among bioluminescent coelenterates has revealed a pronounced uniformity in the structural features of initial reactants, i.e., "luciferins" and photo-protein chromophores, as well as the light-emitter product. This product is structurally identical among the different classes of coelenterates: Hydrozoa (the jellyfish, Aequorea), Anthozoa (the sea cactus, Cavernularia; sea pansy, Renilla; and sea pen, Leioptilus), and very likely also the Scyphozoa (the jellyfish, Pelagia). In each of these instances the reaction product, namely, 2-(p-hydroxy-pnenylacetyl)amino-3-benzyl-5-(p-hydroxyphenyl) pyrazine, is the actual light-emitter, whether it occurs in a Ca2+-triggered photoprotein type of luminescence, or in a "luciferin-luciferase" type. The evidence indicates that in certain coelenterates, e.g., Cavernularia, these two types are equally significant, whereas in others (Renilla and Leioptilus) the "luciferin-luciferase" type predominates over the Ca-triggerable photoprotein type, and finally that only the photoprotein type functions in the luciferaseless jellyfish, Aequorea. In all instances investigated, the structure of the light-emitter prior to the luminescence reaction appears to be essentially the same as that of the chromophore of unreacted aequorin. The product of the luminescence reaction is absent in extracts of non luminous species. However, a product very similar to that of luminescent coelenterates occurs also in representatives of other phyla, including the cephalopod molluscs, e.g., the "firefly squid" Watasenia and probably various ctenophores as well.

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PubMed2026

The chromosomal genome sequence of a staghorn coral, Acropora cf.  manni (Scleractinia: Acroporidae).

We present a genome assembly from a colony sample of Acropora cf. manni (staghorn coral; Cnidaria; Anthozoa; Scleractinia; Acroporidae). The assembly contains two haplotypes with total lengths of 459.26 megabases and 489.30 megabases. Most of haplotype 1 (94.39%) is scaffolded into 14 chromosomal pseudomolecules. Haplotype 2 was assembled to scaffold level. The mitochondrial genome has also been assembled, with a length of 18.48 kilobases. Metagenome binning recovered one bacterial bin from the phylum Chlamydiota.

Acropora cf. manni↗

PubMed2026

The chromosomal genome sequence of the maze coral, Meandrina meandrites (Linnaeus, 1758) (Scleractinia: Meandrinidae) and its associated microbial metagenome sequences.

We present a genome assembly from a specimen of Meandrina meandrites (maze coral; Cnidaria; Anthozoa; Scleractinia; Meandrinidae). The genome sequence has a total length of 551.16 megabases. Most of the assembly (99.25%) is scaffolded into 14 chromosomal pseudomolecules. The mitochondrial genome has also been assembled, with a length of 17.2 kilobases. Gene annotation of this assembly by Ensembl identified 30 464 protein-coding genes. We recovered two bins from the metagenome data.

Meandrina meandrites↗

PubMed2026

The chromosomal genome sequence of the spiny sea fan, Muricea muricata (Pallas, 1766) (Malacalcyonacea: Plexauridae) and its associated microbial metagenome sequences.

We present a genome assembly from a Muricea muricata specimen (spiny sea fan; Cnidaria; Anthozoa; Malacalcyonacea; Plexauridae). The genome sequence has a total length of 453.40 megabases. Most of the assembly (98.45%) is scaffolded into 16 chromosomal pseudomolecules. The mitochondrial genome has also been assembled, with a length of 19.29 kilobases. Gene annotation of this assembly by Ensembl identified 52 164 protein-coding genes. From the metagenome data, we recovered five bins, of which three were high-quality MAGs.

Malacalcyonacea↗

PubMed2026

The chromosomal genome sequence of the lesser starlet coral, Siderastrea radians (Pallas, 1766) (Scleractinia: Rhizangiidae) and its associated microbial metagenome sequences.

We present a genome assembly from a specimen of Siderastrea radians (lesser starlet coral; Cnidaria; Anthozoa; Scleractinia; Rhizangiidae). The genome sequence has a total length of 807.19 megabases. Most of the assembly (94.17%) is scaffolded into 14 chromosomal pseudomolecules. The mitochondrial genome has also been assembled, with a length of 19.38 kilobases. Gene annotation of this assembly by Ensembl identified 47 051 protein-coding genes. From the metagenome data, we recovered two binned metagenomes assigned to the bacterial phylum Bacteroidota and class Bacteroidia.

Scleractinia↗

PubMed2025

Hologenomic insights into the molecular adaptation of deep-sea coral Bathypathes pseudoalternata.

Deep-sea coral ecosystems support biodiversity and nutrient cycling through interactions with symbionts. However, their molecular mechanisms remain unexplored. Here, hologenomic analyses of Bathypathes pseudoalternata are applied to uncover molecular adaptations underpinning host-symbiont interactions. Genomic evidence reveals that B. pseudoalternata exhibits adaptations in nutrient transport, immune response, and lysosomal digestion, reflecting its genomic adjustments for a stable symbiosis. Candidatus Nitrosopumilus bathypathes (78.43% ± 3.65%) is inferred to oxidize host-derived ammonia to synthesize amino acids and vitamins to provision the host. The presence of CRISPR-Cas and restriction-modification (R-M) systems suggests that Ca. Bathyplasma bathypathes and Ca. Thalassoplasma bathypathes (10.68% ± 2.99%) may protect the host from viral infections. Ca. Bathybacter bathypathes (8.39% ± 1.53%) is hypothesized to synthesize heme, lipoic acid, and glutathione, which serve dual functions as antioxidants and nutrients. These findings collectively provide insights into how the hologenome contributes to the survival of B. pseudoalternata in the extreme environment.

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PubMed2026

Diversity and population connectivity of members of the family Eunicidae inhabiting deep-water corals in the North Atlantic.

Eunicid polychaetes are often found in association with Cold Water Corals (CWCs), even establishing symbiotic relationships, such as those described between Desmophyllum pertusum and Eunice norvegica. While genetic connectivity of CWCs across the North Atlantic has been widely studied, little is known about their associated fauna in this regard. Here, we present a study combining a focused analysis of the genetic and genomic connectivity of E. norvegica with a regional assessment of the distribution and evolutionary relationships of three CWC-associated eunicid species from the Cantabrian Sea and the North of the United Kingdom (190-1,230 m depth). An integrative approach using genetic (16S, COI and 18S), morphological and ecological data allowed the identification of the eunicids studied, with new records of Eunice cf. nicidioformis and Leodice cf. antarctica in the Cantabrian Sea, as well as previously undocumented associations with CWC species. In addition, RADseq data contributed to the delimitation of the closely related species E. norvegica and Eunice philocorallia. Moreover, the genetic connectivity of E. norvegica was studied trough a RADseq (1,067 neutral SNPs) approach. Our results indicate a single panmictic population across approximately 2,000 km, suggesting that oceanographic currents facilitate passive dispersal of E. norvegica lecithotrophic larvae, aided by coral host stepping-stones. The connectivity patterns observed for E. norvegica mirror those of D. pertusum, on which the worm is ecologically dependent. Our study highlights the importance of using integrated genetic, morphological and ecological data to characterise and delineate understudied CWC-associated species and improve our understanding of their dispersal capabilities and genetic connectivity to inform future conservation recommendations.

Animals↗

PubMed2026

Integrating genomic distance analyses in the description of a new family, genus, and species of sponge-associated antipatharians (black corals).

Antipatharians (black corals) are among the least studied coral groups, with much of their diversity still undescribed. Here, we present an integrative morphological, phylogenomic and genomic distance study of deep-sea antipatharians sampled in high seas areas of the North Pacific Ocean and from New Zealand's Exclusive Economic Zone. These corals grow on hexactinellid sponges - a unique characteristic in the order Antipatharia. Using a dataset of ultra-conserved elements and exons, combined with morphological analyses, we reconstruct phylogenomic relationships and formally describe a new family (Eidikopathidae fam. nov.), a new genus (Eidikopathesgen. nov.), and two new species (E. korallispongiasp. nov., E. zealandkoralliasp. nov.). Morphologically, the new family is distinguished by a corallum consisting of a network of loose branches that fuse with the sponge skeletal framework. Phylogenomic analyses recovered consistent topologies with strong nodal support, corroborating the distinct evolutionary placement of this sponge-associated lineage. Pairwise genomic distances estimated using the Tamura-Nei model were concordant with patristic genomic distances, identifying Pteridopathidae as the genetically closest family to Eidikopathidae fam. nov., followed by Myriopathidae and Stylopathidae, which were recovered as sister families in the phylogeny. This pattern shows that genomic distance complements, rather than simply mirrors, tree topology by quantifying accumulated sequence divergence among lineages. Together, these results provide the first genomic distance framework for Antipatharia, offering a baseline for future systematic, evolutionary, and biodiversity studies on this fundamental shallow, mesophotic and deep-sea coral group.

Animals↗

PubMed2025

Hybridization as driving force for cryptic species diversity in the Caribbean coral genus Madracis.

Species boundaries in scleractinian corals remain highly elusive due to conflicting patterns between morphological and molecular phylogenies, often caused by morphological plasticity, occurrence of cryptic species, incomplete lineage sorting or introgressive hybridization. Here, we use an integrated systematics approach, which combines reduced representation genome sequencing (nextRAD), micro-morphometric characterization, SEM analyses and compilation of life history traits, to infer phylogenetic relationships among closely related species in the Caribbean coral genus Madracis. In total, we analyzed 235 Madracis specimens from Curaçao and Bermuda collected from 10-90 m depth. Sequence- and SNP-based analyses for 115 samples generated unprecedented species resolution in Madracis, greatly supporting the morphology-based taxonomy of the current, accepted Caribbean species M. senaria, M. decactis, M. formosa, M. carmabi and M. mirabilis (M. auretenra). The exception was M. pharensis, in which we found evidence for three separate lineages, and for which we found signatures of admixture and introgression. These three M. pharensis lineages showed distinct depth distributions (thus classified as shallow, deep and very deep) and were partially distinguishable on the basis of fine microstructural elements of the collumella, septa and coenosteum. Further taxonomic comparisons are needed to formalize these putative cryptic species. Overall, our integrated systematics approach further resolves species relationships in the Caribbean genus Madracis, supports the morphological descriptions for most of the recognized species, but also reveals the existence of cryptic diversity in groups marked by high admixture, thus suggesting hybridization as a driving force in coral species diversity.

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PubMed2025

Limited contributions of bacteria and fungi to coral nutrition revealed by amino acid δ13C analysis.

Corals often form reef ecosystems that support diverse marine life, but they are sensitive to environmental fluctuations that can affect their nutrient acquisition. While coral-associated microbes (e.g., Symbiodiniaceae, bacteria and fungi) may supplement nutrients to coral hosts via metabolite translocation and nutrient recycling, the extent to which these microbial partners contribute to coral autotrophy or heterotrophy remains unclear. Here, we seasonally measure the carbon isotopes of amino acids (δ13CAA) in reef-building coral Pocillopora damicornis and its nutrient sources (e.g., Symbiodiniaceae and particulate organic matter). Regional Bayesian mixing models show that P. damicornis increased autotrophy (from 67.1 to 80.5%), but decreased particulate feeding (from 32.9 to 19.5%) from the cool season to the warm season. Stable essential δ13CAA values (valine, leucine and isoleucine) suggest limited seasonal changes in microbial contributions. Linear discriminant analysis, which combines current and published data from basal organisms (e.g., bacteria and fungi) to coral consumers, also reveals limited bacterial and fungal contributions to coral nutrition. Thus, we advocate that coral nutrition is primarily determined by Symbiodiniaceae translocation and particulate feeding. As these nutritional pathways are highly subject to environmental fluctuations, corals lacking trophic flexibility may suffer more from malnutrition and even population decline under global environmental change.

Anthozoa↗

PubMed2026

Endozoicomonas acroporae enhances coral thermal resilience through host-microbe coordination.

Probiotics hold promise for enhancing coral resilience under climate-driven thermal stress, yet their mechanisms remain poorly understood. Although the bacterial genus Endozoicomonas has been proposed to benefit corals, in vivo evidence of beneficial effects on the host remains limited. Here, we establish Endozoicomonas acroporae Acr-14T as a coral probiotic and characterize its effects on the reef-building coral Stylophora pistillata. We show that E. acroporae Acr-14T enhances host thermal tolerance, colonizes coral tissues, and forms coral-associated microbial aggregates. Microbial profiling indicates that probiotic treatment is associated with reduced relative abundances of opportunistic microbes and enrichment of putatively beneficial taxa. To support transcriptomic analyses, we assembled a chromosome-level genome of S. pistillata clade 1 (Pacific lineage) and found that E. acroporae Acr-14T treatment mitigates heat-induced protein-folding stress and apoptotic signaling. Single-cell transcriptomics further revealed altered expression of genes involved in S-adenosylmethionine (SAMe) metabolism and pro-survival signaling in gastrodermal cells of probiotic-treated corals. Together, our results provide a cell-type-resolved view of host responses linked to Endozoicomonas-mediated coral thermal resilience and offer insight into molecular mechanisms implicated in host-microbe interactions under environmental stress.

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PubMed2026

Developmental Fates of Progenitor/Undifferentiated Cells With Histone Trimethylation Tags in the Stony Coral, Acropora tenuis.

The stony coral, Acropora tenuis, possesses progenitor/undifferentiated cells similar to other anthozoans; however, their developmental potential and fate remain obscure. The present study initially showed that nerve progenitors and undifferentiated-like cells were both tagged with histone H3 trimethylation at Lys 4 and Lys 27, suggesting that Acropora progenitor/undifferentiated cells might be multipotent. A rabbit anti-reverse transcriptase (anti-AtRTase) antibody recognized undifferentiated-like cells in the middle region of the ectodermal layer in embryos 60-85 h post-fertilization. At the larval stages, AtRTase signals were concentrated around the oral pole where the larval ectoderm invaginated to form the pharyngeal stomodeum. Undifferentiated-like cells, but not the apical-most glandular epithelium in the ectoderm, appeared to enter the pharynx. Consistent with this hypothesis, AtRTase signals were continuous from undifferentiated-like cells to the stomodeum. Nerve progenitors (neuroblasts) expressed nerve-specific tubulin beta-III (TUBB3). They differentiated into nerve cells and expressed a neuroblast differentiation-associated protein around the aboral pole of larvae. On the other hand, non-aboral neuroblasts expressed the autophagy-related protein 10 in addition to TUBB3 and developed into vacuolated hyaline cells (VHCs) that penetrated through the ectoderm apicobasally. The present study suggests strongly that ectodermal undifferentiated cells in A. tenuis have the potential to form the stomodeum. In contrast, nerve progenitors possess the dual potential to differentiate into nerve cells and VHCs, which appears to depend on aboral and non-aboral positions.

Animals↗

PubMed2025

Contrasting Patterns of Connectivity Between Populations of Euphotic and Mesophotic Hydroids in Reunion Island Support the Deep Reef Refuge Hypothesis.

In the context of coral reef decline, mesophotic coral ecosystems (MCEs, 30-150 m) offer hope for the recovery of degraded euphotic reefs. The Deep Reef Refuge Hypothesis (DRRH) postulates the potential of mesophotic reefs to reseed euphotic reefs. This hypothesis needs to be further tested by estimating connectivity along the depth gradient. Mesophotic data are lacking worldwide, particularly in the southwestern Indian Ocean (SWIO). Here, using a total of 2218 samples collected at depths ranging from 10 to 103 m, we estimated the connectivity of 7 hydroid species sampled at euphotic, upper, and lower mesophotic depths around Reunion Island using a multi-species comparative framework. Population genetic analyses using 8-17 microsatellite markers per species (80 markers in total) as well as Bayesian inference were performed to estimate population structure and contemporary migration rates to highlight connectivity patterns and directionality of gene flow between depths. The results revealed three main genetic patterns depending on the species: a horizontal stepping stone pattern between areas around the island, a vertical stepping stone pattern between adjacent depths, and a quasi-panmictic pattern. Each species showed some specificity within these patterns, but overall, at least 4 of the 7 species support the assumption of vertical connectivity from the Deep Reef Refuge Hypothesis, highlighting the importance of studying multiple species. The existence of vertical connectivity between euphotic and mesophotic depths in the southwestern Indian Ocean confirms the importance of mesophotic coral ecosystems for conservation efforts and our global understanding of coral reef ecosystem dynamics.

Animals↗

PubMed2026

Assessment of multiple probiotic strains that protect Montipora capitata coral from infection by Vibrio coralliilyticus.

Coral disease outbreaks threaten reef ecosystems, often leading to widespread mortality and declines in coral cover. Outbreaks of tissue loss diseases like acute Montipora white syndrome (aMWS) have impacted coral populations that include the Hawaiian rice coral (Montipora capitata). Multiple strains of Vibrio coralliilyticus are known pathogens, and strain OCN008 has been demonstrated as an etiological agent of aMWS in Hawai'i. Recent work has demonstrated that probiotic bacterial strains can be used to directly treat or prevent transmission (prophylaxis) of coral diseases. Based on their production of zones of inhibition and isolation from disease-resistant corals, Pseudoalteromonas ardens R96, Pseudoalteromonas obscura P94, strain Y97 (the genomic similarity to Pseudoalteromonas piscicida is presented), Pseudoalteromonas umbrosa B95, and Vibrio tetraodonis subsp. pristinus OCN044 were assessed for their ability to impair V. coralliilyticus OCN008 infection of M. capitata during laboratory infection trials. Individual inoculation of each of the five aforementioned strains on M. capitata fragments for 48 h prior to V. coralliilyticus OCN008 inoculation resulted in up to a 93.75% reduction in mortality. These results indicate that strains of Pseudoalteromonas and Vibrio can act as prophylactics to prevent M. capitata mortality from V. coralliilyticus OCN008 infection and provide tools to improve disease resilience for Pacific corals.IMPORTANCECoral disease outbreaks are a growing threat to the continued health of coral reefs, which are already vulnerable ecosystems. Strains of the bacterium Vibrio coralliilyticus are known to infect various coral species worldwide, predominantly causing tissue loss and death of the coral animal. Previous research has indicated that constituents from healthy coral microbiomes can act as probiotics to treat or prevent coral infections, and the discovery of effective probiotics is important in the effort to further develop mitigation tools for disease outbreaks. This work provides a demonstration of probiotic species that can protect coral from tissue loss infections by a strain of Vibrio coralliilyticus and is an example of probiotics developed for coral species in Hawai'i. This work provides new tools for probiotic-based coral protection and evidence for this research as a viable avenue to protect coral in their native environments.

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